Building-plaster



. 25 the surface.

PATENT FF- BUILDlNG-PLASTER.

SPECIFICATION forming part of Letters Patent No. 533,420, dated February5, 18195. Application filed November 9, 1894. Serial No. 528,338. (Nospecimens.)

diana, have invented anew and useful Build- 1ng-P1aster,of which thefollowing is a specification.

This invention contemplates the productlon of a building plaster whereinthe surface,

when dry, will be harder and smoother than heretofore, and wherein thesurface will be free from lath stains.

Ordinarily the surface of building or wall plaster is rough and brittle,and it is neces- I 5 sary to its finished state that a surface coatingor finish be applied, whereby to endow it with a hard and smoothsurface. Again, the

moisture attending the wet plaster is invariably transmitted to thelaths, which causes the wood of which they are composed to give out orexpel a colored substance. This permeates the plaster and shows on theface thereof, making what are known as lath stains, and greatlyimpairing the beauty of Now, by means of my invention thesedisadvantages are overcome; and the invention lies in the compoundingand use of an ingredient for the plaster which I term, for the purposesof trade, the chemical, which is 0 formed of such ingredients as arecapable of performing the functions which the objects of my inventionrequire. Thus the lath stainr ing is prevented by the application ofsulphate of zinc and alum to the laths, which 3 5 acts on themchemically and prevents the giving off of the colored fluid or stainreferred to above.

The plaster is made to harden and to have a smooth glossy surface bycombining with its constituent ingredients flour, sugar, lime,

and oil-cake meal, which elements enter into the composition and, bymeans of a chemical affinity not necessary to be here set forth, causesthem to dry slowly, and this operation,

5 together with certain latent influences which the said elements exert,causes the surface of the plaster to have that appearance and thoseattributes which it is one of the objects of my invention to attain.

The plaster for which my chemical is best adapted is composed of thefollowing ingredients: sand, (sharply formed grains,) eight hundredpounds; plaster of paris, four hundred pounds; fire clay, (pulverized,)thirty pounds; hair, one pound; chemical, twelve pounds. Theseingredients should be G0ll1 bined with the requisite amount of water andmixed into a thoroughly homogeneous mass, as is usual in such cases andas will be understood. It will also be understood that the mixing may beperformed by any suitable means, mechanical or manual. In the aforegoingformula the words sharply-formed grains, preceding sand, mean sand whichis composed of grains having sharp points and edged sides, this beingthe kind of sand usually employed for building purposes. It may also beexplained that fire clay means clay which is similar to that used forfire brick and ground to the requisite degree of fineness.

p The chemical is composed of the following named elements oringredients: alum,

(pulverized) fifty pounds; flour, (wheat) one hundred and fifty pounds;sugar, (granulated) one hundred pounds; lime, (ground) six hundredpounds; oil cake meal, two hundred pounds; sulphate of zinc, twenty-fivepounds. This also should be thoroughly mixed and made as nearlyhomogeneous as possible. There should not, however, be any liquidapplied, since the chemical is kept dry until combined with the plastercompound. In this latter compound the several ingredients, being endowedwith a chemical affinity, combine to produce a new substance, which,owing to its new attributes, effects the several ends before explained.Thus the flour, sugar, lime and oil-cake meal operate as a retarder, tomake the operation of setting slow, gradual and regular, and at the sametime, or consequently, act to give the finished plaster a hard andsmooth surface. Similarly, the alum and sulphate of zinc enter intoassociation with the wood of the lathe and by their influence preventthe throwing off of the stain aforesaid, by counteracting the chemicaloperation which is set up by the combination of the Wet plaster andwood, and. causing the stain to be, not formed.

Having described the invention, I olain1- In testimony that I claim theforegoing as my own I have hereto affixed my signature in the presenceof two Witnesses.

As an ingredient of building plaster, alum, WILLIAM H. AIKMAN. 5 wheatflour, sugar, lime, oil-cake meal, and Witnesses:

sulphate of zinc, combined substantially as LOUIS A. MEYER, and in theproportions stated. JAMES KING.

